Figure 4: Comparison of invasion and colony formation between the parental 4T1 and its derivatives. (a) Matrigel invasion assay. Cells were seeded in BioCoat Matrigel invasion chambers and cell invasion was evaluated 24 h later by counting five adjacent microscope fields at 20x magnification for metastatic cells clinging at the bottom of the membrane. Columns are means ± S.D. of three independent experiments. (b) Indirect independent growth measurement of cells for single-cell colony formation. Cells were seeded in 6-well plates in soft agar and cell colonies were determined 20 days later. Columns are means ± S.D. of three independent experiments.